In order to measure an available band that is a band which is usable for communication between one communication device and the other communication device, there is a case in which each of a plurality of packets is transmitted and received at a predetermined time interval. Note that a series of packets which are transmitted at predetermined time intervals is also referred to as a packet train.
In such a case, one communication device transmits a packet train to the other communication device. Then, the other communication device calculates an available band, based on the transmission intervals and reception intervals of the series of packets transmitted by the one communication device.
PTL 1 discloses a system which calculates a packet loss rate, based on the number of transmitted packets and the number of received packets.